The objective of this proposal is a genetic analysis of the regulation and control of meiosis in male Drosophila melanogaster. We are using two systems to analyze this problem; the analysis of mutants which affect chromosome behavior in meiosis and the analysis of the segregation patterns of translocation and compound autosomes. Two meiotic mutants are being examined. One mutant permits nonhomologous pairing. Studies with this mutant are designed to explore the parameters of the nonhomologous pairing. The second mutant affects the second meiotic division and is chromosome specific. The nature of this specificity will be examined. Various chromosomal aberrations will be analyzed with respect to their segregation patterns. These will include Y - 2 translocations and compound autosomes. In the translocations, we have found that certain types of segregation do not occur. Some compound autosomes do not segregate randomly in males. We anticipate the results from our studies on translocation segregation and compound autosome segregation will permit us to identify those heterochromatic regions that are necessary for chromosome pairing.